From 5ff526f92808bb2a434da0a5d3f4dda2ec2facf4 Mon Sep 17 00:00:00 2001
From: Hauke Petersen <hauke.petersen@fu-berlin.de>
Date: Wed, 16 Dec 2020 23:33:05 +0100
Subject: [PATCH] net/asymcute: fix msgId when publishing QOS0

---
 sys/net/application_layer/asymcute/asymcute.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/sys/net/application_layer/asymcute/asymcute.c b/sys/net/application_layer/asymcute/asymcute.c
index 122e3837fc..440fea119b 100644
--- a/sys/net/application_layer/asymcute/asymcute.c
+++ b/sys/net/application_layer/asymcute/asymcute.c
@@ -879,8 +879,14 @@ int asymcute_publish(asymcute_con_t *con, asymcute_req_t *req,
         goto end;
     }
 
-    /* get message id */
-    req->msg_id = _msg_id_next(con);
+    /* set MsgId only for QoS 1 and 2, else it must be set to 0 */
+    if (((flags & MQTTSN_QOS_MASK) == MQTTSN_QOS_1) ||
+        ((flags & MQTTSN_QOS_MASK) == MQTTSN_QOS_2)) {
+        req->msg_id = _msg_id_next(con);
+    }
+    else {
+        req->msg_id = 0;
+    }
 
     /* assemble message */
     size_t pos = _len_set(req->data, data_len + 6);